An agricultural harvesting machine such as a combine includes a harvesting header and a feeder housing or crop elevator which removes the crop material from the field, gather the crop material and transport the crop material to a threshing separating and cleaning mechanism located in the combine.
The cleaned grain is deposited in a grain tank located at the top of the combine. When the grain tank becomes full, an unloading auger, which is supported on and positioned alongside of the combine during harvesting, is moved to its unloading position in which the auger extends approximately perpendicular to the longitudinal axis of the combine. A vehicle drives alongside the combine into which the grain is to be unloaded, such as a semi-trailer, and the unloading auger is actuated to discharge the grain into the vehicle.
For small stemmed crops such as wheat, soybeans, etc., the combine typically carries and drives a header with a reciprocating knife at the leading edge of the header. The particular header illustrated herein is a draper header, although the invention is not limited to a draper header. The reciprocating knife is alternatively called a sickle, sickle bar, cutter bar or similar terms. The crop is cut using the reciprocating knife and falls forward onto laterally extending conveyor belts that carry the crop to a central aperture of the header. The cut crop passes through the aperture and into the feeder house.
To insure the belts can be driven, they must be properly tensioned on their respective idler rollers and drive rollers. Sufficient tension must be maintained across the width of the drive rollers that they can transfer sufficient power to the belt to carry the crop inward toward the feederhouse. In modern designs, the conveyor belts and cutter bar are supported on arms that extend forward from the frame of the header. As these arms travel over the ground, they lift up and down with respect to each other, flexing and twisting the cutter bar and the conveyor belts as they follow the contours of the ground.
In U.S. Pat. No. 6,202,397 B1, a tensioning apparatus is illustrated for a center draper belt conveyor in which a translatable end roller is supported on two sliding roller mounts extending from a conveyor frame. A bell crank mounted on a stationary from extending across the middle of the conveyor permits a spring force to be applied to the roller, wherein the spring extends generally parallel to the rollers. The force is applied to the roller carriage at its midpoint to provide an even pressure across the width of the belt. This belt is fixed to a frame and cannot twist.
In U.S. Pat. No. 2,631,421, a windrow harvester attachment for a tractor has a laterally extending conveyor belt that is tensioned by extending opposed pairs of links located at each end of the adjustable drive roller. The links are fixed to a stationary front rail and a stationary rear rail. The geometry (see FIG. 4) is such that a constant tension is applied across the width of the belt.
In U.S. Pat. No. 2,762,183, a windrow harvester is shown with an end roller supported on two nested, telescopic cylinders supporting opposing ends of the end roller with a spring disposed in each cylinder and with the telescopic cylinders mounted to a stationary front rail and a stationary rear rail. These identical telescoping supports apply a similar force to both ends of the rollers, thereby providing a constant tension across the width of the belt. The endmost roller is not supported to pivot or twist, nor is the conveyor itself supported to pivot or twist.
Accommodating the flexing and twisting of the conveyor belts is difficult using traditional belt tensioners. The rollers must be able to push outward against the belt and also pivot side to side to distribute the tension across the belt. If the tension in the conveyor belt cannot be distributed across its width, the belt may break, may slip, or may suffer premature wear.
It is an object of this invention to provide a header with a belt tensioner that accommodates the flexing and twisting of the conveyor belts and distributes the tension more evenly across the width of the conveyor belts than these prior art arrangements.